Thermionic amplifier



Jan. 5, 1937. E. w. B. GILL ET AL v 2,067,043

THERMIONIC AMPLIFIER Original Filed June 1, 1928 INVENTOR V ERNESTWALTER BRUDENELLGILL KS)?! ALDSON ATT NEY Patented Jan. 5, 1937 UNITEDSTATES PATENT OFFIQE.

THERMIONIC' AMPLIFIER Delaware.

Application June 1, 1928, Serial No. 282,089. Re-

newed May 14, 1931. 1927 16 Claims.

This invention relates to thermionic amplifiers and detectors, and hasfor its principal object to provide an improved thermionic amplifier ordetector suitable for use at high frequencies and in which liability toself-oscillation, due to inter-electrode and the like capacity in theamplifier, shall be reduced to a minimum.

According to this invention a thermionic amplifier or detector comprisesa four-electrode 1O thermionic valve, an output circuit associated withone electrode of said valve, and input means arranged in push-pullfashion between two other electrodes of the said valve, the inputcircuit being completed from a point on said input means to the fourthelectrode and the whole arrangement being such that the part or whole ofthe effect of interelectrode and the like capacity between the outputelectrode of the valve and one input electrode thereof is wholly or inpart compensated by the effect of inter-electrode and the like capacitybetween the said output electrode and the other input electrode.

Preferably the point on the input means which is connected to the fourthelectrode is made variable.

A more complete understanding of the invention will be had from thefollowing specification, and from the specification when read inconnection with the drawing in which;

Figure 1 shows one form of the invention in which the internal capacitybetween the plate and outer grid balances the capacity between the outerand inner grid while Figure 2 shows a modification of Figure 1.

Referring to Figure 1 of the drawing, which shows one way of carryingout the invention, an input oscillatory circuit, comprising aninductance l and shunt variable condenser 2, is connected between theplate 3 and inner grid 4 of a four-electrode valve 5, the said plate andinner grid thus constituting the input electrodes of the valve.

A variable tapping point 6 upon the inductance l in the inputoscillatory circuit l--Z is connected (through a grid bias battery I, ifre quired) to the cathode 8 of the valve.

The outer grid 9 of the valve is connected through an output tunedcircuit comprising an inductance l0 and shunt variable condenser ll,and. thence through a high tension battery l2 to the cathode. Theamplified output of the valve may be tapped off in any well known wayfrom the output electrode, i. e. the outer grid.

It will be seen that with this arrangement the effective plate-outergrid capacity tends to neu- In Great Britain June 8.

tralize the eifective inner grid-outer grid capacity and by adjustmentof the variable tapping point upon the inductance in the input circuit,substantially complete neutralization may be obtained.

For slight departures from complete neutralization the amplifier may bebrought to reaction by adjustment of the filament current.

In a modification shown in Figure 2 a small and preferably adjustableexternal condenser is 10 provided in parallel with the lesser capacity.Such a'condenser may be provided as shown in dotted lines in Figure 2 atE3 or at M, according to whether the plate-outer grid or outer gridinnergrid is the lesser capacity. With the condenser provided at I4 (as inthe figure) the point 6 may be adjusted towards the top of theinductance I, thus obtaining a larger proportion of the oscillatingpotential on the inner grid, which is, of course, the more efiectiveelectrode from the point of view of control.

Although the term push-pull has been employed in describing the presentinvention, the said term is not to be understood to imply that controlis shared equally between the two electrodes between which input meansare arranged in what has hereinbefore been termed pushpull fashion,although in known push-pull arrangements the push is generally equal tothe pull. In arrangements in accordance with the present invention,practically all the control is efiected by the grid electrode, to whichthe input means are connected, although such effect as the anode has asregards control is beneficial.

Having now particularly described and ascertained the nature of our saidinvention and in what manner the same is to be performed, we declarethat what we claim is:-

1. In an electron discharge device amplifier comprising a four electrodevalve, an output cir- 4G cuit connected between the outer grid andcathode of said valve, an input circuit including an input inductancearranged push-pull fashion between the anode and inner grid of saidvalve, and connecting means between a point on said input inductance andthe cathode of said valve.

2.111 an electron discharge device amplifier comprising a four electrodevalve, an output circuit connected between the outer grid and cathode ofsaid valve, an input circuit including an 5 input inductance arrangedpush-pull fashion between the anode'and inner grid of said valve, andvariable connecting means between a point on said input inductance andthe cathode of said valve.

3. In an electron discharge device amplifier comprising a four electrodevalve, an output circuit connected between the outer grid and cathode ofsaid valve, an input circuit including an input inductance arrangedpush-pull fashion between the anode and inner grid of said valve,connecting means between a point on said input inductance and thecathode of said valve, and a variable condenser connected between theouter grid and an adjacent electrode of said valve.

4. An electron discharge device amplifier including a thermionic valvehaving anode, cathode, control grid and an auxiliary electrode, anoutput circuit connected between said auxiliary electrode and saidcathode, an input circuit including an inductance connected directlybetween the inner grid and anode of said valve and a variable tapconnecting a point on said inductance to said cathode, the position ofsaid tap being such that the alternating potential applied through theinherent capacity of said tube from the auxiliary electrode to thecontrol grid is compensated by the alternating potential applied throughthe inherent capacity of said tube from the auxiliary electrode to saidanode.

5. In combination, an electron discharge tube provided with a cathode,an anode and two intermediate electrodes, a resonant circuit connectedbetween one of said electrodes and the cathode,and a second resonantcircuit connected between the remaining intermediate electrode and theanode, the potentials of said anode and last mentioned electrode beingmaintained in opposite phase relation.

6. In combination, an electron discharge tube provided with a cathode,anode, control grid and auxiliary electrode, means for applying apotential to said electrode which is positive with respect to saidcathode, a resonant circuit coupled to said electrode and cathode, and aradio frequency oscillation circuit coupled between said anode and grid,the potentials on said anode and grid being in opposite phase relation.

7. A high frequency circuit comprising an electron discharge tubeprovided with an anode, cathode, grid and an auxiliary electrodedisposed between the grid and anode, a source of energy for supplying apotential to said electrode which is positive with respect to saidcathode, a resonant circuit between the latter and said cathode, and asource of high frequency oscillations coupled to said grid and anode.

8. A high frequency circuit comprising an electron discharge tubeprovided with an anode, cathode, grid and an auxiliary electrodedisposed between the grid and anode, means for applying a potential tosaid electrode which is positive with respect to said cathode, aresonant circuit connected to the latter, a source of high frequencyoscillations coupled to said grid and anode, and a connection betweensaid cathode and a point on said resonant circuit.

9. A radio frequency receiver comprising an electron discharge tubeprovided with an anode, cathode, grid and auxiliary electrode, means formaintaining the latter positively biased with respect to the anode andcathode, a tunable output resonant circuit connected in the auxiliaryelectrode circuit, and an independent radio frequency oscillationcircuit connected to the anode.

10. In an electron tube circuit, a thermionic tube including a cathode,a grid and an anode, an input circuit comprising a source of potentialdisposed between said anode and cathode, an output circuit including asecond source of potential and disposed between said grid and cathode,said source of potential in said input circuit being connected tosubject said anode to a negative charge and said source of potential insaid output circuit being adapted to subject said grid to a positivecharge.

11. In combination, in a receiver of high frequency signal waves, anelectron discharge tube provided with a cathode, a cold electrode andtwo additional cold electrodes, an output circuit connected between saidfirst cold electrode and the cathode, and a resonant signal inputcircuit connected between the two additional cold electrodes, the signalpotentials of said two additional cold electrodes being maintained inopposite phase relation, and a connection between the cathode and apoint on said resonant input circuit.

12. In an electron tube circuit, an electron tube including a cathode, agrid and an anode, a circuit comprising a source of potential disposedbetween said anode and said cathode, an output circuit including asecond source of potential and disposed between said grid and cathode,said source of potential in said first circuit being connected tosubject said anode to a negative charge and said source of potential insaid output circuit being adapted to subject said grid to a positivecharge.

13. In an electron tube system, an electron tube having at least onecathode, one grid, and one anode, a source of alternating currentconnected to said anode and said cathode, a source of direct currentgrid potential, and an output circuit connected through said source ofgrid potential to said grid and said cathode for applying to said grid apotential positive with reference to said cathode.

14. In an electron tube system, an electron tube having at least onecathode, one grid, and one anode, a source of alternating currentconnected to said anode and said cathode, means connected in seriesbetween said source and said anode and cathode for maintaining saidanode at a determined potential with reference to said cathode, a sourceof direct current grid potential, and an output circuit connectedthrough said source of grid potential to said grid and said cathode forapplying to said grid a potential positive with reference to saidcathode.

15. In combination, an electron discharge tube comprising a cathode,anode, inner and outer grids, a tunable resonant input circuit coupledbetween said anode and inner grid, and a tunable resonant output circuitcoupled between said outer grid and cathode, and a connection from saidcathode to said input circuit.

16. In combination, an electron discharge tube comprising a cathode,anode, inner and outer grids, a tunable resonant input circuit coupledbetween said anode and inner grid, and a tunable resonant output circuitcoupled between said outer grid and cathode, and means for maintainingsaid anode and inner grid negative with respect to said cathode.

ERNEST WALTER BRUDENELL GILL. ROBERT HOPE DONALDSON.

